Power tool system and battery pack thereof

ABSTRACT

A power tool system and a battery pack. The battery pack includes a housing provided with a socket, and two battery cell groups received in the housing. Each battery cell group has a positive electrode and a negative electrode. The socket has four conductive terminals respectively and electrically connected to the electrodes of two battery cell groups. Two battery cell groups can be switched between isolated state and series connected state to output two different voltages through two conductive terminals with different polarities being disconnected or connected to each other, and the two conductive terminals with different polarities are respectively connected to two battery cell groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a US application which claims the priority of CNApplication Serial No. 201811425584.1, filed on Nov. 27, 2018, thedisclosures of which are hereby incorporated by reference in theirentirety.

TECHNICAL FIELD

The present invention relates to a dual voltage battery pack and a powertool system.

BACKGROUND

Battery pack as a rechargeable power source is increasingly used forsupplying power for outdoor tools, especially for cordless power tools.It's very convenience to use Lithium-ion batterie pack as an energysource to drive a motor of the power tool because the battery pack canbe removed from the tools and rechargeable by an external chargingdevice. Because the motor of the cordless power tool has a rated voltageand need to be driven by corresponding battery pack which can output thecorresponding voltage, and different cordless power tools have differentrated-voltage motors, so a plurality of battery packs which can supplydifferent voltages for corresponding tools need to be carried when theworker operates different cordless power tools in the outdoors. It'svery inconvenient for the operator because of the larger load caused bythe battery packs.

Therefore, there is a requirement to provide an improved battery packand a power tool system to overcome the problems described above.

SUMMARY OF INVENTION

the present invention provides a battery pack which can output twodifferent voltages and a power tool system.

In order to achieve the object, the present invention provides a batterypack comprising a housing having a socket located thereon and twobattery cell groups received in the housing, each battery cell grouphaving a positive electrode and a negative electrode, the socket havinga plurality of terminals received therein, the terminals including fourconductive terminals respectively and electrically connected tocorresponding electrode of two battery cell groups, two battery cellgroups being switched between isolated state and series connected stateto output two different voltages through two conductive terminals withdifferent polarities being disconnected or connected to each other, andthe two conductive terminals with different polarities beingrespectively connected to two battery cell groups.

In an exemplary embodiment, the two conductive terminals with differentpolarities are adjacent and separate to each other, and two battery cellgroups are isolated with each other in the battery pack and output a lowvoltage.

In an exemplary embodiment, the two conductive terminals with differentpolarities are adjacent and connected to each other, and two batterycell groups are connected with each other in series in the battery packand output a high voltage.

In an exemplary embodiment, four conductive terminals are arrangedadjacent to each other, and the two conductive terminals with differentpolarities are located in the middle, and two adjacent conductiveterminals located on two sides have same polarity.

In an exemplary embodiment, four conductive terminals are arrangedadjacent to each other, and two conductive terminals with differentpolarities are located on one side of the four conductive terminals, andtwo adjacent conductive terminals which are located in the middle havesame polarity.

In an exemplary embodiment, the two conductive terminals with differentpolarities each defines a contacting arm, and the contacting arms of thetwo conductive terminals with different polarities are close butseparate to each other.

In an exemplary embodiment, two battery cell groups are switched fromisolated state to series connected state to output a high voltagethrough changing the connection of two contacting arms from separatestate to connected state.

In an exemplary embodiment, two battery cell groups are in seriesconnected state and output a high voltage when the contacting arms ofthe two conductive terminals are connected to each other.

In an exemplary embodiment, the two conductive terminals with differentpolarities each defines a contacting arm, and the contacting arms of thetwo conductive terminals with different polarities are directlyconnected to each other through two contacting arms abutting with eachother.

In an exemplary embodiment, two battery cell groups are switched fromseries connected state to isolated state to output a low voltage throughchanging the connection of two contacting arms from electrical connectedstate to electrical isolated state.

In an exemplary embodiment, two battery cell groups are in isolatedstate and output a low voltage when the contacting arms of the twoconductive terminals are isolated from each other.

In an exemplary embodiment, the two conductive terminals with differentpolarities each further defines a pair of main arms located on one sideof the contacting arm, and the main arms are in idle state when thecontacting arms of the two conductive terminals abutting with eachother.

The present invention also provides a power tool system comprising: ahigh rated-voltage power tool having a first male plug; a lowrated-voltage power tool having a second male plug; and a battery packsupplying power to the high or low rated-voltage power tool connectedthereto, the battery pack including a housing having a socket locatedthereon and two battery cell groups received in the housing, the socketdefining a plurality of terminals received therein, the terminalsincluding four conductive terminals, each battery cell group defining apositive electrode and a negative electrode respectively andelectrically connected to corresponding conductive terminal, two batterycell groups being switched between isolated state and series connectedstate through two conductive terminals with different polarities beingdisconnected or connected to each other, and the two conductiveterminals with different polarities being respectively connected to twobattery cell groups, and the battery pack outputting a low voltagethrough connecting two battery cell groups in parallel when the secondmale plug being connected to the socket and a high voltage throughconnecting two battery cell groups in series when the first male plugbeing connected to the socket.

In an exemplary embodiment, two conductive terminals with differentpolarities are adjacent and separate to each other, and two battery cellgroups are isolated with each other in the battery pack.

In an exemplary embodiment, the second male plug has four contactingterminals corresponding to four conductive terminals of the batterypack, and the four contacting terminals are respectively andelectrically connected to corresponding four conductive terminals whentwo cell groups are connected with each other in parallel.

In an exemplary embodiment, the first male plug has one connectingterminal simultaneously and electrically connected with the twoconductive terminals with different polarities and two conductingterminals respectively connected with corresponding conductive terminalof another two conductive terminals of the socket, and two battery cellgroups are connected to each other in series through the connectingterminal simultaneously connecting one of the two conductive terminalswith different polarities to the other of two conductive terminals withdifferent polarities.

In an exemplary embodiment, the connecting terminal of the first maleplug is simultaneously and electrically connected to the two conductiveterminals with different polarities through two opposite sides thereof.

In an exemplary embodiment, the two conductive terminals with differentpolarities are adjacent and connected to each other, and two batterycell groups are connected with each other in series in the battery pack.

In an exemplary embodiment, the first male plug of the highrated-voltage power tool has two conducting terminals respectively andelectrically connected to corresponding conductive terminals of the resttwo conductive terminals in the four conductive terminals, and theconductive terminals with different polarities are disengaged when thefirst male plug is assembled to the socket.

In an exemplary embodiment, the second male plug of the lowrated-voltage power tool has two contacting terminals and an insulatingrib located in the middle of two contacting terminals, and eachcontacting terminal defines a pair of contacting arms branched at theend thereof for connecting with corresponding conductive terminal of thesocket, and the insulating rib is inserted into the connected twoconductive terminals of the socket to electrically isolate these twoconductive terminals, and two cell groups are connected with each otherin parallel when the insulating rib of the second male plug is clampedby the two conductive terminals with different polarities.

In an exemplary embodiment, four conductive terminals are arrangedadjacent to each other, and the two conductive terminals with differentpolarities are located in the middle, and two adjacent conductiveterminals located on two sides have same polarity.

In an exemplary embodiment, four conductive terminals are arrangedadjacent to each other, and two conductive terminals with differentpolarities are located on one side of the four conductive terminals, andtwo adjacent conductive terminals which are located in the middle havesame polarity.

In an exemplary embodiment, two conductive terminals with differentpolarities defines a gap formed therebetween, and the connectingterminal is inserted into the gap for simultaneously and electricallyconnecting the two conductive terminals with different polaritiestogether.

In an exemplary embodiment, the second male plug has an insulating riblocated in the middle of four contacting terminals, and the insulatingrib is inserted into two conductive terminals in the middle toelectrically isolated these two conductive terminals.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a battery pack in accordance with afirst embodiment of the present invention.

FIG. 2 is a perspective view of a socket of the battery pack shown inFIG. 1.

FIG. 3 is a schematic view of the electrical connection between theconductive terminals of the socket and the electrodes of two batterycell groups shown in FIG. 1.

FIG. 4 is a partial perspective view of a power tool system according tothe first embodiment of the present invention, showing the connectionstatus of the socket of the battery pack in FIG. 2 and a first male plugof a high rated-voltage power tool when the battery pack outputting ahigh voltage for the high rated-voltage power tool, and the base of thefirst male plug is not shown.

FIG. 5 is an exploded perspective view of the first male plug of thehigh rated-voltage power tool in accordance with the first embodiment ofthe present invention.

FIG. 6 is a partial perspective view of a power tool system according tothe first embodiment of the present invention, showing the connectionstatus of the socket of the battery pack and a second male plug of a lowrated-voltage power tool when the battery pack outputting a low voltagefor the low rated-voltage power tool, and the main housing of the secondmale plug is not shown.

FIG. 7 is an exploded perspective view of the second male plug of thepower tool in accordance with the first embodiment of the presentinvention.

FIG. 8 is a partial perspective view of a power tool system according tothe second embodiment of the present invention, showing the connectionstatus of the socket of the battery pack and a second male plug of a lowrated-voltage power tool when the battery pack outputting a low voltagefor the low rated-voltage power tool, and the main housing of the secondmale plug is not shown.

FIG. 9 is a schematic view of the electrical connection between theconductive terminals of the socket and the electrodes of two batterycell groups shown in FIG. 8.

FIG. 10 is an exploded perspective view of the second male plug of thelow rated-voltage power tool in accordance with the second embodiment ofthe present invention.

FIG. 11 is a partial perspective view of a power tool system accordingto the second embodiment of the present invention, showing theconnection status of the socket of the battery pack and a first maleplug of a high rated-voltage power tool when the battery pack outputtinga high voltage for the high rated-voltage power tool, and the base ofthe first male plug is not shown.

FIG. 12 is an exploded perspective view of the first male plug of thehigh rated-voltage power tool shown in FIG. 11 according to the secondembodiment of the present invention.

FIG. 13 is a schematic view of the electrical connection between theconductive terminals of the socket and the electrodes of two batterycell groups of the battery pack according to the third embodiment of thepresent invention.

FIG. 14 is a partial perspective view of a power tool system accordingto the third embodiment of the present invention, showing the connectionstatus of the socket of the battery pack and a second male plug of a lowrated-voltage power tool when the battery pack outputting a low voltagefor the low rated-voltage power tool, and the main housing of the secondmale plug is not shown.

FIG. 15 is a partially exploded perspective view of the second male plugof the low rated-voltage power tool shown in FIG. 14.

FIG. 16 is a partial perspective view of a power tool system accordingto the third embodiment of the present invention, showing the connectionstatus of the conductive terminals of the battery pack and a first maleplug of a high rated-voltage power tool when the battery pack outputtinga high voltage for the high rated-voltage power tool, and the base ofthe first male plug is not shown.

FIG. 17 is a schematic view of the electronical connection between theconductive terminals of the socket and the electrodes of two batterycell groups of the battery pack according to the fourth embodiment ofthe present invention.

FIG. 18 is a partial perspective view of a power tool system accordingto the fourth embodiment of the present invention, showing theconnection status of the conductive terminals of the battery and a firstmale plug of the high rated-voltage power tool when the battery packoutputting high voltage for the high rated-voltage power tool, and thebase of the first male plug is not shown.

FIG. 19 is an exploded perspective view of the f male plug of the highrated-voltage power tool according to the fourth embodiment of thepresent invention.

FIG. 20 is a partial perspective view of a power tool system accordingto the fourth embodiment of the present invention, showing theconnection status of the conductive terminals of the battery pack and asecond male plug of the low rated-voltage power tool when the batterypack outputting a low voltage for the low rated-voltage power tool, andthe main housing of the second male plug is not shown.

DESCRIPTION OF EMBODIMENTS

The present invention will be described in detail below with referenceto the drawings and specific embodiments.

It is also to be noted that, in order to avoid obscuring the inventionin unnecessary detail, the structures and/or processing steps onlyclosely related to the aspects of the present invention are shown in thedrawings and the other details having little relationship with thisinvention is omitted.

In addition, it should be noted that the terms “comprising”,“including”, or any other variants are intended to encompass anon-exclusive inclusion, such that a process, method, article, or devicethat comprising a plurality of elements includes not only those elementsbut also the elements that are not explicitly listed, or the elementsthat are inherent to such a process, method, item, or device.

FIGS. 1 to 7 illustrate a power tool system according to a firstembodiment of the present invention. The power tool system includes ahigh rated-voltage power tool (not shown) having a first male plug 120,a low rated-voltage power tool (not shown) having a second male plug130, and a battery pack 100 optionally connected to the high or lowrated-voltage power tools for supplying power to corresponding powertool. The battery pack 100 has a socket 110 located on the top thereofand optionally connected with the first male plug 120 or the second maleplug 130. The battery pack 100 outputs a low voltage to the lowrated-voltage power tool through the socket 110 electrically connectingwith the second male plug 130 and a high voltage to the highrated-voltage power tool through the socket 110 electrically connectingwith the first male plug 120.

Referring to FIG. 1 to FIG. 3, a battery pack 100 used for supplyingpower to corresponding power tool also includes a housing 101 and afirst and second battery cell groups 102, 103 received in the housing101. Each battery cell group 102, 103 has a plurality of battery cellsconnected in series and has same battery cells. Each battery cell group102, 102 is electrically connected to the socket 110 through a circuitboard (not shown) which is received in the housing 101. The two batterycell groups 102, 103 are connected with each other in parallel when thesocket 110 is electrically connected with the second male plug 130. Thetwo battery cell groups 102, 103 are connected with each other in serieswhen the socket 110 is electrically connected with the first male plug120.

Referring to FIG. 2, the socket 110 includes a body 104 formed on thetop of the housing 101 and six terminals received in the body 104 in arow from left to right. Six terminals include one communicating terminal115, four conductive terminals 114, 112, 113, 111 and one chargingterminal 116. The communicating terminal 115 and the charging terminal116 are respectively disposed at two opposite sides of all conductiveterminals 114, 112, 113,111, so as to prevent the battery pack 100 fromdamage when charging at a high voltage level and prolong the servicelife of the battery pack 100. The charging terminal 116 is used fortransferring charger to charge the battery cells of the battery cellgroups 102, 103 when the battery pack 100 is connected to a power sourcethrough a charger (not shown).

The conductive terminals 111, 112, 113, 114 respectively connected tothe positive and negative electrodes of two battery cell groups 102, 103through a circuit board (not shown) are used to achieve the electricallyconnection between the battery pack 100 and the corresponding power toolwhen connected to the corresponding male plug 120, 130, so as to achievethe power supplying function of the battery pack 100 for the power tool.Two conductive terminals 111, 112 are respectively and electricallyconnected to the positive and negative electrodes of the first batterycell group 102. The other two conductive terminals 113, 114 arerespectively connected to the positive and negative electrodes of thesecond battery cell group 103. Specifically, the conductive terminal 111is electrically connected to the positive electrode of the first batterycell group 102. The conductive terminal 112 is electrically connected tothe negative electrode of the first battery cell group 102. Theconductive terminal 113 is electrically connected to the positiveelectrode of the second battery cell group 103. The conductive terminal114 is electrically connected to the negative electrode of the secondbattery cell group 103.

Six terminals 111, 112, 113, 114, 115, 116 are configured with twodifferent structures. The communicating terminal 115, the chargingterminal 116 and two conductive terminals 111, 114 are configured withsame structure. The rest two conductive terminals 112, 113 have samestructure but different with that of the communicating terminal 115.Each of the communicating terminal 115, the charging terminal 116 andtwo conductive terminals 111, 114 has two contacting arms to clampcorresponding contacting terminal of the first or second male plug 120,130. Two conductive terminals 112, 113 are symmetrically arranged in themiddle of six terminals and each has one contacting arm for contactingwith corresponding contacting terminal of the first or second male plug120, 130.

Specifically, the conductive terminals 114, 112, 113, 111 are disposedin the body 104 from left to right. Two conductive terminals 111, 114are respectively disposed at the opposite sides of two conductiveterminals 112, 113. Specifically, the conductive terminal 114 isdisposed at the left side of the conductive terminal 112. The conductiveterminal 111 is disposed at the right side of the conductive terminal113. The conductive terminal 112 is disposed at the left side of theconductive terminal 113. Two conductive terminals 112, 113 are close toeach other. The contacting arms of the conductive terminals 112, 113 areclose but separate with each other. The first and second battery cellgroups 102, 103 are isolated with each other in the battery pack 100.

Due to the layout of these four conductive terminals 114, 112, 113,111,the contacting arms of the conductive terminals 112, 113 are easily andmechanically connected or disconnected to each other. Therefore, thebattery cell groups 102, 103 are easily switched between two statesthrough the contacting arms of the conductive terminals 112, 113. Onestate is that two battery cell groups 102, 103 are connected with eachother in series to output a high voltage. The other state is that twobattery cell groups 102, 103 are connected with each other in parallelto output a low voltage.

Specifically, when the contacting arms of two conductive terminals 112,113 are connected to each other, two battery cell groups 102, 103 areconnected in series and the battery pack 100 can output a high voltagefor the high rated-voltage power tool connected thereto. When thecontacting arms of two conductive terminals 112, 113 are isolated ordisconnected with each other, two battery cell groups 102, 103 areisolated with each other and the battery pack 100 can output a lowvoltage for the low rated-voltage power tool connected thereto.

In this embodiment, the conductive terminal 111 is the first positiveterminal 111, the conductive terminal 112 is the first negative terminal112, the conductive terminal 113 is the second positive terminal 113 andthe conductive terminal 114 is the second negative terminal 114. Thesecond negative terminal 114, the first negative terminal 112, thesecond positive terminal 113 and the first positive terminal 111 aredisposed on the battery pack 100 from left to right. In this embodiment,the communicating terminal 115 is located at the left side of the secondnegative terminal 114 and the charging terminal 116 is located at theright side of the first positive terminal 111. The first negativeterminal 112 and the second positive terminal 113 are selectivelydisconnected or connected in two different mechanical connection states.In one state, the two battery cell groups 102, 103 are connected witheach other in series for outputting a high voltage. In another state,the two battery cell groups 102, 103 are connected with each other inparallel to output a low voltage.

Referring to FIG. 4 and FIG. 5, the conductive terminals 114,112,113,111 of the battery pack 100 cooperates with the first male plug120 to output a high voltage for the high rated-voltage power tool (notshown). The first male plug 120 includes a stepped base 126 and aplurality of first male terminals 121, 122, 123, 124, 125 received inthe stepped base 126. The first male terminals 121, 122, 123, 124, 125include four first male conducting terminals 121, 122, 123, 124 and oneconnecting terminal 125 disposed in the same row and respectivelyconnected to six terminals of the battery pack 100. The connectingterminal 125 is located at the middle of all the first male terminals121, 122, 123, 124, 125 and can be connected with both conductiveterminals 112, 113 when the first male plug 120 is inserted into thesocket 110. The connecting terminal 125 has a width approximately samewith the distance between the contacting arms of two conductiveterminals 112, 113.

Four male conducting terminals 121, 122, 123, 124 are respectivelyconnected to the communicating terminal 115, two conductive terminals114, 111 and the charging terminal 116 through clamped by correspondingtwo arms of corresponding terminals of the socket 110 when the firstmale plug 120 is inserted into the socket 110. Specifically, when thefirst male plug 120 is inserted into the socket 110 of the battery pack100, the male conducting terminal 121 is clamped by two contacting armsof the communicating terminal 115. The male conducting terminal 122 isclamped by two contacting arms of the conductive terminal 114. The maleconducting terminal 123 is clamped by two contacting arms of theconductive terminal 111. The male conducting terminal 124 is clamped bytwo contacting arms of the charging terminal 116. The connectingterminal 125 is clamped together by the contacting arms of theconductive terminals 112, 113, so as to electrically connect thenegative electrode of the first battery cell group 102 to the positiveelectrode of the second battery cell group 103. Therefore, the first andsecond battery cell groups 102, 103 are connected with each other inseries and the battery pack 100 outputs a high voltage for the highrated voltage power tool through the negative conductive terminals 114and the positive conductive terminal 111 thereof.

Specifically, when the first male plug 20 of the high rated-voltagepower tool is connected to the socket 110 of the battery pack 100, onlythe electrical connections formed between the male conducting terminal121 and the communicating terminal 115, the male conducting terminal 122and the conducting terminal 114, the male conducting terminal 123 andthe conducting terminal 111 are achieved between the first male plug 20and the socket 110 of the battery pack 100. Specifically, the electricalconnection formed between the male conducting terminal 122 and theconducting terminal 114 is used to transfer the communication betweenthe battery pack 100 and the high rated-voltage power tool. Theelectrical connections formed between two sets of terminals, forexample, the male conducting terminal 122 and the conducting terminal114, the male conducting terminal 123 and the conducting terminal 111are used to supply power from the battery pack 100 to the highrated-voltage power tool. The connecting terminal 125 is only used toelectrically connected the conducting terminal 112 to the conductingterminal 113 in the battery pack 100, so as to make two battery cellgroups 102, 103 connected with each other in series. No electricalconnection between the battery pack 100 and the high rated-voltage powertool is achieved by the connecting terminal 125 and two conductingterminals 112, 113. The connecting terminal 125 is only used to achievethe electrical connection between two battery cell groups 102, 103.

The charging terminal 116 is used when the battery pack 100 is connectedto an external power source for charging, and it doesn't work when thebattery pack 100 is connected to the power tool, so that the chargingterminal 116 and the male conducting terminal 124 only have a mechanicalconnection but not an electrical connection. The cooperation of the maleconducting terminal 124 and the charging terminal 116 can enhance themating strength between the first male plug 120 and the battery pack100. Correspondingly, the first male plug 120 can be provided with onlythree first male terminals 121, 122, 123, and without the maleconducting terminal 124.

Referring to FIG. 6 and FIG. 7, the conductive terminals 114, 112, 113,111 of the battery pack 100 of the present invention cooperates with thesecond male plug 130 to output a low voltage for of a low rated-voltagepower tool (not shown). The second male plug 130 includes a main housing135 corresponding to the body 104 of the socket 110 and a plurality ofsecond male terminals 131, 132, 133, 134 receiving in the main housing135. The main housing 135 defines an insulating rib 136 at the bottomthereof, for electrically insulating two conductive terminals 112, 113when the second male plug 130 is connected to the socket 110 of thebattery pack 100. The insulating rib 136 extends along the main housing135 from a rear-to-front direction. The insulating rib 136 integrallyformed with the main housing 135 is located corresponding to the spaceformed between two conductive terminals 112, 113. The insulating rib 135is also located in the middle of the second male terminals 131, 132,133, 134. Specifically, the insulating rib 135 is located between twosecond male terminals 132, 133 for achieving the electrical insulationof two contacting terminals 132, 133 when the second mal plug 130 isconnected to the socket 110 of the battery pack 100.

The second male terminals configured with two different type includefour contacting terminals 131, 132, 133, 134 which are corresponding tosix terminals of the battery pack 100. Four contacting terminals 131,132, 133, 134 are disposed in the main housing 135 from left to right.Two contacting terminals 131, 134 have same structure and each definesonly one contacting arm respectively clamped by two contacting arms ofcorresponding communicating terminal 115 or charging terminal 116. Thefunction of the contacting terminals 131 is same with that of theconducting terminal 121 of the first mal plug 120 which is describedabove. The function of the contacting terminal 134 is same with that ofthe conducting terminal 124 of the first male plug 120 which isdescribed above.

Two contacting terminals 132, 133 have same structure which is differentwith that of the contacting terminals 131, 134 and each defines a pairof contacting arms 1321, 1322, 1331, 1332 corresponding to conductiveterminals 114, 112, 113, 111. Specifically, the contacting terminal 132is configured with a pair of contacting arms 1321, 1322 branched at theend thereof. The contacting arm 1321 is clamped by two contacting armsof the conductive terminal 114 and the contacting arm 1322 is connectedto the contacting arm of the conductive terminal 112. The contactingterminal 133 also defines two contacting arms 1331, 1332 branched at theend thereof. The contacting arm 1331 is electrically connected to thecontacting arm of the conductive terminal 113 and the other contactingarm 1332 is clamped by two contacting arms of the conductive terminal111. The contacting terminal 132 is simultaneously connected with twoconductive terminals 114, 112 and the contacting terminal 133 issimultaneously connected with two conductive terminals 112, 111 when thesecond male plug 130 is connected to the socket 110.

Therefore, the electrical connection between the socket 110 and thesecond male plug 130 is achieved together by the contacting arms of theconductive terminal 114 clamping one contacting arm 1321 of thecontacting terminal 132, the contacting arm of the conductive terminal112 connecting with the other contacting arm 1322 of the contactingterminal 132, the contacting arm of the conductive terminal 113contacting with one contacting arm 1331 of the contacting terminal 133and the contacting arms of the conductive terminal 111 clamping theother contacting arm 1332 of the contacting terminal 133. Due to thestructures of two contacting terminals 132, 133 of the second male plug130 and the conductive terminals 114, 112, 113, 111 of the socket 110,the first battery cell group 102 and the second battery cell group 103are connected with each other in parallel, the battery pack 100 output alow voltage to the low rated-voltage power tool through the electricalconnections between the conducting terminals 114, 112,113, 111 of thesocket 110 and two contacting terminals 132, 133 of the second male plug130.

Specifically, the contacting arm 1322 of the contacting terminal 132 isclosed to the contacting arm 1331 of the contacting terminal 133. Theinsulating rib 136 is located between the contacting arm 1322 of thecontacting terminal 132 and the contacting arm 1331 of the contactingterminal 133 and separate these two contacting terminals 132 and 133, soas to prevent the contacting terminals 132, 133 from circuit shorting.The insulating rib 136 has a length longer than that of the contactingarms 1322, 1331.

In this embodiment, two conductive terminals 112, 113 are isolated witheach other in the battery pack 100, so that two battery cell groups 102,103 are isolated with each other. When the first male plug 120 of thehigh rated-voltage power tool is assembled on the socket 110 of thebattery pack 100, the connecting terminal 125 of the first male plug 120is clamped by corresponding contacting arms of two conductive terminals112, 113, the conducting terminal 122 of the first male plug 120 isclamped by two contacting arms of the conductive terminal 114, and theconducting terminal 123 is clamped by two contacting arms of theconductive terminal 111, so that the conductive terminals 114, 112, 113,111 are connected with each other in series, two battery cell groups102, 103 of the battery pack 100 are connected with each other inseries, therefore, the battery pack 100 outputs a high rated-voltage forthe high rated-voltage power tool through the connection between thesocket 100 and the first male plug 120. The battery cell groups 102. 103can be switched between isolated state and series connection state whendisconnecting or connecting the socket 110 of the battery pack 100 tothe first male plug 120 of the high rate-voltage power tool. When thesecond male plug 130 of the low rated-voltage power tool is assembled onthe socket 110 of the battery pack 100, the contacting terminal 133 ofthe second male plug 130 is simultaneously connected with two conductiveterminals 111, 113, the contacting terminal 132 is simultaneouslyconnected with two conductive terminals 112 and 114, so that twoconductive terminals 111, 113 are connected in parallel and twoconductive terminals 112, 114 are connected in parallel. Therefore, twobattery cell groups 102, 103 are connected with each other in paralleland the battery pack 100 outputs a low voltage for the low rated-voltagepower tool. The battery cell groups 102, 103 can be switched betweenisolated state and parallel connection state when disconnecting orconnecting the socket 110 of the battery pack 100 to the second maleplug 130 of the low rated-voltage power tool.

FIGS. 8 to 12 illustrate a power tool system in accordance with thesecond embodiment of the present invention. The power tool systemincludes a battery pack 200 with a socket 210, a high rated-voltagepower tool with a first male plug 230 and a low rated-voltage power toolwith a second male plug 220 in accordance with the second embodiment ofthe present invention. The differences between the power tool systems inthe first and second embodiments are that the first male plug 230 of thehigh rated-voltage power tool in the second embodiment is configured assame with the second male plug 130 of the low rated-voltage power toolin the first embodiment and the second male plug 220 of the lowrated-voltage power tool in the second embodiment is configured as samewith the first male plug 120 of the high rated-voltage power tool in thefirst embodiment except lacking the connecting terminal 125. Two batterycell groups 202, 203 in the second embodiment are connected with eachother in series when four conductive terminals 211, 212, 213, 214 arerespectively and electrically connected to the corresponding positiveand negative electrodes of the first and second battery cell group 202,203, but two battery cell groups 102, 103 in the first embodiment areisolated with each other when four conductive terminals 111, 112, 113,114 are respectively and electrically connected to the correspondingpositive and negative electrodes of the first and second battery cellgroup 102, 103. The communicating terminal 215, the charging terminal216 and two conductive terminals 214, 211 in the second embodiment areconfigured as same with corresponding communicating terminal 115, thecharging terminal 116 and two conductive terminals 114, 111 in the firstembodiment. The reason caused the different battery packs 200, 100 indifferent embodiments is the different structures of the sockets 210,110. Specifically, the conductive terminals 212, 213 are respectivelydifferent with corresponding conductive terminals 112, 113. Eachconductive terminal 212, 213 formed integrally from a conductive sheetdefines a pair of main contacting arms 2121, 2131 and an auxiliarycontacting arm 2122, 2132. But conductive terminal 112, 113 in the firstembodiment each only has one contacting arm. The main contacting arms2121, 2131 have same structure with that of the conductive terminals215, 214, 211, 216. Two auxiliary contacting arms 2122, 212 are locatedclose to each other and electrically connected with each other, so as tomake two battery cell groups 202, 203 in the second embodiment beingconnected with each other in series in the battery pack 200.

Referring to FIGS. 8 and 10, when the second male plug 220 of the lowrated-voltage power tool is assembled to the socket 210 in the secondembodiment, the contacting terminal 221 is clamped by two contactingarms of the communicating terminal 215, one contacting arm of thecontacting terminal 222 is clamped by a pair of contacting arms of theconductive terminal 214, the other contacting arm of the contactingterminal 222 is clamped by two main contacting arms of the conductiveterminal 212, the insulating rib 225 is clamped by two auxiliarycontacting arms 2122, 2132, one contacting arm of the contactingterminal 223 is clamped by two main contacting arms of the conductiveterminal 213 and the other contacting arm of the contacting terminal 223is clamped by two contacting arms of the conductive terminal 211, andthe contacting terminal 224 is clamped by two contacting arms of thecharging terminal 216. The insulating rib 225 is separate the auxiliarycontacting arm 2122 of the conductive terminal 212 from the auxiliarycontacting arm 2132 of the conductive terminal 213, so that thecontacting terminal 222 of the second male plug 220 is simultaneouslyconnected with two conductive terminals 214, 212 of the socket 210, thecontacting terminal 223 of the second male plug 220 is simultaneouslyconnected with two conductive terminals 213, 211. Therefore, two batterycell groups 202, 203 are connected with each other in parallel due totwo conductive terminals 214, 212 being connected with each other inparallel and two conductive terminals 213, 211 being connected with eachother in parallel. And then the battery pack 200 outputs a low voltageto the low rated-voltage power tool through the socket 210 and thesecond male plug 220. Two battery cell groups 202, 203 can be switchedbetween series connection state and parallel connection state throughdisconnecting or connecting the socket 210 of the battery pack 200 tothe second male plug 220 of the low rated-voltage power tool.

Referring to FIGS. 11 and 12, when the first male plug 230 of the highrated-voltage power tool is assembled to the socket 210 of the batterypack 200 in the second embodiment, the conducting terminal 231 isclamped by two contacting arms of the communicating terminal 215, theconducting terminal 232 is clamped by two contacting arms of theconductive terminal 214, the conducting terminal 233 is clamped by twocontacting arms of the conductive terminal 211, the conducting terminal234 is clamped by two contacting arms of the charging terminal 216. Themain contacting arms 2121, 2131 of the conductive terminals 212, 213 aredisengaged but the auxiliary contacting arm 2122 of the conductiveterminal 212 is connected to the auxiliary contacting arm 2132 of theconductive terminal 213. So that two battery cell groups 202, 203 areconnected with each other in series, the battery pack 200 outputs a highvoltage for a high rated-voltage power tool through the socket 210 andthe first male plug 230.

In the second embodiment, two conductive terminals 212, 213 areconnected with each other in the battery pack 200, so that two batterycell groups 202, 203 are connected with each other in series in thebattery pack 200. When the first male plug 230 of the high rated-voltagepower tool is assembled on the socket 210 of the battery pack 200, theconducting terminal 232 is clamped by two contacting arms of theconductive terminal 214, the conducting terminal 233 is clamped by twocontacting arms of the conductive terminal 211, so that the conductiveterminals 214, 212, 213, 211 are connected to each other in seriesthrough the conductive terminal 212 being connected with the conductiveterminal 213, two battery cell group 202, 203 are connected with eachother in series. Therefore, the battery pack 200 outputs a high voltagefor the high rated-voltage power tool through the connection between thesocket 210 and the first male plug 230. When the second male plug 220 ofthe low rated-voltage power tool is assembled on the socket 210 of thebattery pack 200, the contacting terminal 222 is simultaneouslyconnected with two conductive terminals 214, 212, and the contactingterminal 223 is simultaneously connected with two conductive terminals213, 211, and the insulating rib 225 is simultaneously connected withtwo auxiliary arms 2122, 2131 and separated the connection between twoconductive terminals 212, 213. So that the conductive terminals 214,213, 212, 211 are connected with each other in parallel through thecontacting terminals 222, 223. Therefore, two battery cell groups 202,203 are connected with each other in parallel and the battery pack 200outputs a low voltage for the low rated-voltage power tool. Two batterycell groups 202, 203 can be switched between series connection state andparallel connection state when disconnecting or connecting the socket210 of the battery pack 200 to the second male plug 220 of the lowrated-voltage power tool.

FIGS. 13 to 16 illustrate a power tool system in accordance with thethird embodiment of the present invention. The power tool systemincludes a battery pack 300 provided with a socket 310, a highrated-voltage power tool provided with a first male plug 330 and a lowrated-voltage power tool with a second male plug 320 in the thirdembodiment of the present invention. The socket 310 of the battery pack300 in this embodiment has same structure with the socket 110 of thebattery pack 100 in the first embodiment, except that the conductiveterminal 313 is connected to the negative electrode of the secondbattery cell group 303, and the conductive terminal 314 is connected tothe positive electrode of the second battery cell group 303. But in thefirst embodiment, the conductive terminal 113 is connected to thepositive electrode of the second battery cell group 103 and theconductive terminal 314 is connected to the negative electrode of thesecond battery cell group 103. Two battery cell groups 203, 303 areisolated with each other in the battery pack 300 before the battery pack300 is connected to the high or low rated-voltage power tools. Twobattery cell groups 302, 303 can be switched between isolated state andparallel connected state through disconnecting or connecting the socket310 of the battery pack 300 to the second male plug 320 of the lowrated-voltage power tool. Two battery cell group 302, 303 can be alsoswitched between isolated state and series connected state throughdisconnecting or connecting the socket 310 of the battery pack 300 tothe first male plug 330 of the high rated-voltage power tool.

The second male plug 320 of the low rated-voltage power tool in thethird embodiment has similar structure with the first male plug 120 ofthe high rated-voltage power tool in the first embodiment, except thatthe contacting terminal 322 of the second male plug 320 in the thirdembodiment is formed as a whole by integrating tow conductive terminals122, 123 of the first male plug 120 in the first embodiment. Therefore,when the second male plug 320 of the low rated-voltage power tool (notshown) is connected to the socket 310 of the battery pack 300 in thethird embodiment, the contacting terminal 322 is simultaneouslyconnected with two conductive terminals 314, 313 at the same timethrough two contacting arms of the conductive terminal 314 clamping onecontacting arm of the contacting terminal 322 and two contacting arms ofthe conductive terminal 311 clamping the other contacting arm of thecontacting terminal 322. So that two positive electrodes of two batterycell groups 302, 302 are connected with each other in parallel. Theconnecting terminal 323 of the second male plug 320 is simultaneouslyconnected with two conductive terminals 312, 313. So that two positiveelectrodes of two battery cell groups 302, 302 are connected with eachother in parallel. Such that two battery cell groups 302, 302 areconnected with each other in parallel when the second male plug 320 ofthe low rated-voltage power tool is assembled on the socket 310 of thebattery pack 300. And the battery pack 300 can output a low voltage forthe low rated-voltage power tool through connecting the socket 310 tothe second male plug 320. Two battery cell groups 302, 302 can beswitched between isolated state and parallel state through disconnectingor connecting the battery pack 300 to the low rated-voltage power tool.The contacting terminal 321 is clamped by two contacting arms of thecommunicating terminal 315. The contacting terminal 324 is clamped bytwo contacting arms of the charging terminal 316, referring to FIG. 14.

Referring to FIG. 16, the first male plug 330 of the high rated-voltagepower tool in the third embodiment has similar structure with the secondmale plug 130 of the low rated-voltage power tool in the firstembodiment, except that two conducting terminals 332, 333 are isolatedand separated with each other. When the first male plug 330 is assembledto the socket 310 of the battery pack 300, the conducting terminal 331is clamped by two contacting arms of the communicating terminal 315, theconnecting terminal 335 is simultaneously connected with two conductiveterminals 314, 312, the conducting terminal 332 is contacting with thecontacting arm of the conductive terminal 313, the conducting terminal333 is clamped by two contacting arms of the conductive terminal 311,and the conducting terminal 334 is clamped by two contacting arms of thecharging terminal 316. So that two battery cell groups 302, 303 areconnected with each other in series due to the conductive terminal 314connected to the connective terminal 312 through the connecting terminal335 of the first male plug 330 and the battery pack 300 output a highvoltage to the high rated-voltage power tool through the connectionbetween the socket 310 and the first male plug 330. Two battery cellgroups 302, 303 can be switched between isolated state and seriesconnected state through disconnecting or connecting the socket 310 ofthe battery pack 300 to the first male plug 330 of the highrated-voltage power tool.

FIGS. 17 to 20 illustrate a power tool system in accordance with thefourth embodiment of the present invention. the power tool systemaccording to the fourth embodiment includes a battery pack 400 with asocket 410, a high rated-voltage power tool with a first male plug 420and a low rated-voltage power tool with a second male plug 430. Thebattery pack 400 in the fourth embodiment has similar structure with thebattery pack 200 in the second embodiment and shown in FIG. 11, exceptthat the conductive terminal 414 is electrically connected to thepositive electrode of the second battery cell group 403 and theconductive terminal 413 is electrically connected to the negativeelectrode of the second battery cell group 403. While the conductiveterminal 214 is electrically connected to the negative electrode of thesecond battery cell group 203 and the conductive terminal 213 iselectrically connected to the positive electrode of the second batterycell group 203 in the second embodiment. So that the negative electrodesof two battery cell groups 402, 403 are connected with each otherthrough the auxiliary contacting arm 4122 of the conductive terminal 412contacting the auxiliary contacting arm 4132 of the conductive terminal413.

Referring FIG. 19, the first male plug 420 of the high rated-voltagepower tool in this embodiment is configured as same structure with thatof the second male plug 220 of the low rated-voltage power tool shown inFIG. 10 in the second embodiment, except two conducting terminals 422,423 are isolated and separated with each other, while the contacting arm223 in the second embodiment is integrated together as a whole. When thefirst male plug 420 of the high rated-voltage power tool is assembled tothe socket 410 of the battery pack 400, the conducting terminal 421 isclamped by two contacting arms of the communicating terminal 415, theconnecting terminal 425 is simultaneously connected with two conductiveterminals 414, 412 through one contacting arm thereof being clamped bytwo contacting arms of the conductive terminal 414 and the othercontacting arm thereof being clamped by two main contacting arms 4121 ofthe conductive terminal 412. The insulating rib 416 is simultaneouslycontacted with the auxiliary arm 4122 of the conductive terminal 412 andthe auxiliary arm 4132 of the conductive terminal 413. The conductingterminal 422 is clamped by two main contacting arms 4131 of theconductive terminal 413. The conducting terminal 423 is clamped by twocontacting arms of the conductive terminal 411 and the conductingterminal 424 is clamped by two contacting arms of the charging terminal416. Therefore, two battery cell groups 402, 403 are connected with eachother in series through the connecting terminal 425 connecting theconductive terminal 414 to the conductive terminal 412 and theinsulating rib 426 electrically insulating two conductive terminals 412and 413. The battery pack 400 output a high voltage to the highrated-voltage power tool through the socket 410 is connected to thefirst male plug 420.

Referring to FIG. 20, the second male plug 430 of the low rated-voltagepower tool in the fourth embodiment is configured as same with that ofthe second male plug 320 of the low rated-voltage power tool shown inFIG. 14 in the third embodiment. When the second male plug 430 in thisembodiment is assembled to the socket 410 of the battery pack 400, thecontacting terminal 431 is clamped by two contacting arms of thecommunicating terminal 415, one contacting arm 4321 of the contactingterminal 431 is clamped by two contacting arms of the conductiveterminal 414, the other contacting arm 4322 of the contacting terminal431 is clamped by two contacting arms of the conductive terminal 413,the contacting terminal 433 is clamped by the auxiliary contacting armsof two conductive terminals 412, 413, the contacting terminal 434 isclamped by two contacting arms of the charging terminal 416. So that twoconductive terminals 414, 411 are connected to each other through thecontacting terminal 431, two conductive terminals 412, 413 are connectedto each other through the contacting terminal 433. Therefore, twobattery cell groups 402, 403 are connected with each other in parallelthrough four conductive terminals 414, 413, 412, 411 and the batterypack 400 output a low voltage to the low rated-voltage power toolthrough the socket 410 is connected to the second male plug 430.Therefore, the first and second battery cell groups 402, 403 can beswitched between series connected state and parallel connected statethrough the battery pack 400 being selectively connected to the firstmale plug 420 of the high rated-voltage power tool or the second maleplug 430 of the low rated-voltage power tool in the fourth embodiment.The battery pack 400 can selectively output a high or low voltagethrough connected to the high or low rated-voltage power tool.

In summary, the battery pack of the present invention comprises two setsof battery cells and four conductive terminals respectively connected tothe two sets of battery cells, two of four conductive terminals areprovided with different mechanical connected states formed therebetween.And two sets of the battery cells in the battery pack are isolated orserially connected with each other through these two conductiveterminals with different polarity being disconnected or connected witheach other. Two sets of the battery cells are always isolated with eachother when these two conductive terminals having same polarity. Acontacting terminal disposed on a male plug of a high rated-voltagepower tool can change the mechanical connection state of two differentpolarity conductive terminals from isolated state to series connectedstate. An insulating rib disposed on a male plug of a low rated-voltagepower tool can change the mechanical connection state of two differentpolarity conductive terminals from series connected state to isolatedstate. Two set of battery cells can be connected with each other inseries or in parallel through the electrical connections formed betweenfour conductive terminals of the battery pack and the conducting orcontacting terminals of the high or low rated-voltage power tool whenthe high or low rated-voltage power tool connected to the battery pack.The battery pack output different voltages through switching theconnection between two set of battery cells caused by the electricalconnection formed between four terminals and the conducting orcontacting terminals of corresponding power tool. so that the batterypack is widely used.

Although, the present invention has been described above with referenceto specific embodiments, it is not intended to be limited to thespecific form set forth herein. Rather, the invention is limited only bythe accompanying claims.

In the claims, the term “comprises/comprising” does not exclude thepresence of other elements or steps. Furthermore, although individuallylisted, a plurality of means or elements may be implemented by e.g. asingle unit or processor. Additionally, although individual features maybe included in different claims, these may possibly advantageously becombined, and the inclusion in different claims does not imply that acombination of features is not feasible and/or advantageous. Inaddition, singular references do not exclude a plurality. The terms “a”,“an”, “first”, “second” etc., do not preclude a plurality. Referencesigns in the claims are provided merely as a clarifying example andshall not be construed as limiting the scope of the claims in any way.

We claim:
 1. A battery pack, comprising: a housing having a socketlocated thereon, the socket having a plurality of terminals receivedtherein, the terminals including four conductive terminals; and twobattery cell groups received in the housing and each having a positiveelectrode and a negative electrode respectively and electricallyconnected to the corresponding conductive terminal of the socket;wherein two battery cell groups can be switched between isolated stateand series connected state to output two different voltages through twoconductive terminals with different polarities being disconnected orconnected to each other, and wherein the two conductive terminals withdifferent polarities are respectively connected to two battery cellgroups.
 2. The battery pack according to claim 1, wherein the twoconductive terminals with different polarities are adjacent and separateto each other, and wherein two battery cell groups are isolated witheach other in the battery pack and output a low voltage.
 3. The batterypack according to claim 2, wherein four conductive terminals arearranged adjacent to each other, and wherein the two conductiveterminals with different polarities are located in the middle, andwherein two adjacent conductive terminals located on two sides have samepolarity.
 4. The battery pack according to claim 1, wherein the twoconductive terminals with different polarities are adjacent andconnected to each other, and wherein two battery cell groups areconnected with each other in series in the battery pack and output ahigh voltage.
 5. The battery pack according to claim 4, wherein fourconductive terminals are arranged adjacent to each other, and whereinthe two conductive terminals with different polarities are located inthe middle, and wherein two adjacent conductive terminals located on twosides have same polarity.
 6. The battery pack according to claim 2,wherein four conductive terminals are arranged adjacent to each other,and wherein two conductive terminals with different polarities arelocated on one side of the four conductive terminals, and wherein twoadjacent conductive terminals which are located in the middle have samepolarity.
 7. The battery pack according to claim 2, wherein the twoconductive terminals with different polarities each defines a contactingarm, and wherein the contacting arms of the two conductive terminalswith different polarities are close but separate to each other.
 8. Thebattery pack according to claim 7, wherein two battery cell groups areswitched from isolated state to series connected state to output a highvoltage through changing the connection of two contacting arms fromseparate state to connected state.
 9. The battery pack according toclaim 7, wherein two battery cell groups are in series connected stateand output a high voltage when the contacting arms of the two conductiveterminals are connected to each other.
 10. The battery pack according toclaim 4, wherein the two conductive terminals with different polaritieseach defines a contacting arm, and wherein the contacting arms of thetwo conductive terminals with different polarities are directlyconnected to each other through two contacting arms abutting with eachother.
 11. The battery pack according to claim 9, wherein two batterycell groups are switched from series connected state to isolated stateto output a low voltage through changing the connection of twocontacting arms from electrical connected state to electrical isolatedstate.
 12. The battery pack according to claim 9, wherein two batterycell groups are in isolated state and output a low voltage when thecontacting arms of the two conductive terminals are isolated from eachother.
 13. The battery pack according to claim 10, wherein the twoconductive terminals with different polarities each further defines apair of main arms located on one side of the contacting arm, and whereinthe main arms are in idle state when the contacting arms of the twoconductive terminals abutting with each other.
 14. A power tool system,comprising: a high rated-voltage power tool having a first male plug; alow rated-voltage power tool having a second male plug; and a batterypack supplying power to the high or low rated-voltage power toolconnected thereto, including: a housing having a socket located thereon,the socket defining a plurality of terminals received therein, theterminals including four conductive terminals, and two battery cellgroups received in the housing and each defining a positive electrodeand a negative electrode respectively and electrically connected tocorresponding conductive terminal; wherein two battery cell groups canbe switched between isolated state and series connected state throughtwo conductive terminals with different polarities being disconnected orconnected to each other, and wherein the two conductive terminals withdifferent polarities are respectively connected to two battery cellgroups, and wherein the battery pack outputs a low voltage throughconnecting two battery cell groups in parallel when the second male plugis connected to the socket and a high voltage through connecting twobattery cell groups in series when the first male plug is connected tothe socket.
 15. The power tool system according to claim 14, wherein twoconductive terminals with different polarities are adjacent and separateto each other, and wherein two battery cell groups are isolated witheach other in the battery pack.
 16. The power tool system according toclaim 15, wherein the second male plug has four contacting terminalscorresponding to four conductive terminals of the battery pack, andwherein the four contacting terminals are respectively and electricallyconnected to corresponding four conductive terminals when two cellgroups are connected with each other in parallel.
 17. The power toolsystem according to claim 16, wherein the first male plug has oneconnecting terminal simultaneously and electrically connected with thetwo conductive terminals with different polarities and two conductingterminals respectively connected with corresponding conductive terminalof another two conductive terminals of the socket, and wherein twobattery cell groups are connected to each other in series through theconnecting terminal simultaneously connecting one of the two conductiveterminals with different polarities to the other of two conductiveterminals with different polarities.
 18. The power tool system accordingto claim 17, wherein the connecting terminal of the first male plug issimultaneously and electrically connected to the two conductiveterminals with different polarities through two opposite sides thereof.19. The power tool system according to claim 14, wherein the twoconductive terminals with different polarities are adjacent andconnected to each other, and wherein two battery cell groups areconnected with each other in series in the battery pack.
 20. The powertool system according to claim 19, wherein the first male plug of thehigh rated-voltage power tool has two conducting terminals respectivelyand electrically connected to corresponding conductive terminals of therest two conductive terminals in the four conductive terminals, andwherein the conductive terminals with different polarities aredisengaged when the first male plug is assembled to the socket.
 21. Thepower tool system according to claim 20, wherein the second male plug ofthe low rated-voltage power tool has two contacting terminals and aninsulating rib located in the middle of two contacting terminals, andwherein each contacting terminal defines a pair of contacting armsbranched at the end thereof for connecting with corresponding conductiveterminal of the socket, and wherein the insulating rib is inserted intothe connected two conductive terminals of the socket to electricallyisolate these two conductive terminals, and wherein two cell groups areconnected with each other in parallel when the insulating rib of thesecond male plug is clamped by the two conductive terminals withdifferent polarities.
 22. The power tool system according to claim 21,wherein four conductive terminals are arranged adjacent to each other,and wherein the two conductive terminals with different polarities arelocated in the middle, and wherein two adjacent conductive terminalslocated on two sides have same polarity.
 23. The power tool systemaccording to claim 18, wherein four conductive terminals are arrangedadjacent to each other, and wherein the two conductive terminals withdifferent polarities are located in the middle, and wherein two adjacentconductive terminals located on two sides have same polarity.
 24. Thepower tool system according to claim 18, wherein four conductiveterminals are arranged adjacent to each other, and wherein twoconductive terminals with different polarities are located on one sideof the four conductive terminals, and wherein two adjacent conductiveterminals which are located in the middle have same polarity.
 25. Thepower tool system according to claim 17, wherein two conductiveterminals with different polarities defines a gap formed therebetween,and wherein the connecting terminal is inserted into the gap forsimultaneously and electrically connecting the two conductive terminalswith different polarities together.
 26. The power tool system accordingto claim 16, wherein the second male plug has an insulating rib locatedin the middle of four contacting terminals, and wherein the insulatingrib is inserted into two conductive terminals in the middle toelectrically isolated these two conductive terminals.